LI-COR has combined solid-state optical technology with near-infrared (NIR) fluorescent dye chemistry to detect DNA with extremely high sensitivity. The investigators propose to extend this proven NIR fluorescence technology to the detection of proteins on membranes. The low native background of biomolecules in the NIR region creates the potential for 1000-fold greater sensitivity than competing technologies. In Phase I, they developed a second-generation "breadboard" two-dimensional (2D) NIR scanner that produces sensitive, high quality image-data and established the technical merit and feasibility of labeling proteins with NIR dyes. NIR-labeled proteins were detected with extremely high sensitivity (two orders of magnitude higher than radio-iodination), and the attached dye did not disrupt protein function in a transcytosis assay system. In Phase II, they propose to label antibodies with NIR dyes for highly sensitive immunological detection of proteins on Western blots and slot blots. The sensitivity, specificity, and linearity of NIR methodology will be carefully assessed, and a prototype 2D scanner for imaging of Western blots will be developed based upon the existing "breadboard" instrument. The investigators claimed that the speed and simplicity of direct NIR detection technology, combined with its high sensitivity, will provide many advantages over commonly used methods such as chemiluminescent and radioisotopic detection. PROPOSED COMMERCIAL APPLICATION: The prototype NIR scanner and reagents will be developed for commercial use as an alternative to conventional Western blotting and other types of membrane-based detection.